Manufacture of artificial silk



. iv v:

iatented Oct- 11,

UN )L oatoy MANUFACTURE OF ARTIFICIAL SILK Harry Donald Mudford, Blackley, Manchester,

England, assignor to Imperial Chemical Industries Limited, a corporation of Great Britain 11 No Drawing. Application November 23, 1935, Se-

rial No. 51,272. In Great Britain December 28,

18 Claims.

A? This invention relates to artificial cellulosic bodies, and particularly to artificial fibers and threads. The invention also relates to improvements in dyeing. The invention also relates to new compositions of matter useful in the manufacture of artificial oellulosic bodies. The invention also relates to cellulosic fibers and threads and to methods of making them light-fast when delustered and dyed with direct dyes. The invention will be described for purposes of illustration in its application to the manufacture of regenerated cellulose fiber, but it is to be understood that this particular description does not limit the invention which is applicable to all situations in which an artificial cellulosic body is delustered with a titanium delustrant and dyed with a direct dye.

In the earlier days of its manufacture rayon was lustrous, but more recently a delustered material has found the greater favor. Of the delustrants so far discovered, the best is titanium dioxide. The delustered material including titanium dioxide has a fine appearance and good properties but it fails in this respect that regenerated cellulose so delustered, when dyed with a direct dye, is far more fugitive to light, particularly in the Wet state, than the undelustered material, and cellulose esters and ethers when dyed with a direct dye and when so delustered a e far more fugitive to light, particularly in the dry state, than the undelustered material. This condition has heretofore forced the abandonment of a large number of most satisfactory dyes and the substitution of more expensive colprs,

Q; It is an object of this invention to manufactur'e delustered rayon which is light-fast when dyed with direct cottondyes. Another object of the invention is to prepare light-fast delustered rayon dyed with direct cotton dyes by economically and technically satisfactory processes. An-

.other object of the invention is to prepare delustered rayon which will be light-fast when dyed with direct dyes. Another object of the invention is to prepare a composition of matter useful in the manufacture of delustered rayon. Other objects of the invention will be in part apparent to persons skilled in the art and in part hereinafter set forth.

(D1) The objects of the invention are accomplished, generally speaking, by treating the titanium delustrant with a compound of chromium or of one of the metals in the chromium group. The process has considerable variation which adapts it to varieties of materials and of delustering agents and the time of application may be chosen practically at will, but in all such variatio the above principle should be incorporated.

In one process of using my invention titanium dioxide which is to be used for the delustering of rayon is treated previously to its incorporation in a spinning mass with a water-soluble chromium compound (for instance a water-soluble chromium salt). The delustrant so prepared is then incorporated with the cellulose solution before spinning and the cellulosic solution is spun in the usual way. The resulting delustered artificial silk, when dyed with direct coloring matters, does not tend to fade rapidly when exposed to daylight.

{lf'glnstead of treating the titanium dioxide previous to incorporation in the spinning mass with a compound of chromium, there may be added to the spinning mass a mixture of titanium dioxide and a water-soluble chromium compound.

lg .,;In a preferred form of the invention the use of a water-soluble chromium compound will probably be preferred, but water-insoluble chromium compounds can also be used. For instance, there can be incorporated with titanium dioxide freshly precipitated chromium hydroxide, or titanium dioxide can be mixed with a soluble chromium salt in the presence of a reagent that will precipitate chromium hydroxide on the titanium dioxide. Such mixtures may be incorporated with delustering solutions and used for delustering in the moist condition, or they may be dried, in which case more or less chromium oxide will be formed from the chromium hydroxide. Again, one may mix together finely divided chromium sesquioxide and titanium dioxide and use it for delustering.

{H} In the manner of treatment set forth above, and of which Examples I, II, III, and IV hereinafter are specimen, the delustered artificial silk itself is not treated with a chromium compound, which is in itself an advantage.

Example I The treatment of the titanium dioxide is effected by means of a solution of 3 parts of potassium bichromate and 1 part formic acid in 1,000 parts of water, the procedure being otherwise the same as that of Example I. In place of the potassium bichromate and formic acid there may be used 2 parts of chromic acid.

Example III The liquor contains 10 parts of chromium chloride or chromium fluoride per litre but otherwise the procedure is as Example I.

Example IV Finely divided titanium dioxide treated as in any of the above examples is incorporated with a viscose spinning mass and a finished thread produced in the known manner. It is then dyed with one per cent of Chlorazol Fast Black BK. The dyeing in the wet condition will be found faster to light than one produced on viscose artificial silk thread which is delustered with untre ted titanium dioxide.

I. In another method of using the invention, th rayon is spun in the usual way and is treated with a chromium-containing compound, for instance a hot aqueous solution of a water-soluble chromium salt, and with or without rinsing and/or drying, and dyed with direct colors in the usual way. In the practice of this form of the invention, regenerated cellulose is made according to any of the known methods, for instance by ejecting viscose or cuprammonium cellulose solutions containing delustrant into the customary regenerating bath and by processing the threadin the usual way. In the process, however, preferably after the viscose solution has been set, the rayon is immersed in an aqueous solution of a chromium salt for a length of time sufficient to make effective the action of the chromium salt. The length of time will be selected by the chemist to secure the optimum results at the temperature at which the treatment is carried out. The aqueous bath containing the chromium salt is preferably heated in order to lessen the time required for the treatment. At a temperature of 85 C. a 0.3% aqueous solution of sodium bichromate will produce a satisfactory result in about half an hour. The time will vary with the temperature and concentration of the bath. It is not essential to heat the bath, but improved results are secured thereby. The concentration of the chromium salt is also to a con-,

siderable extent a matter of choice. Extremely low concentrations, in the neighborhood of 0.3 to 0.5% normally give excellent results and, consequently, for reasons of economy, stronger conce trations are unnecessary.

J Following the treatment of the regenerated cellulose with the solution of the chromium salt, the regenerated cellulose may be rinsed and dried and dyed. The rinsing and drying may be omitted if desired. If the regenerated cellulose article isdried before dyeing, the chromium treatment may follow the drying, but it is considered advantageous to carry out the treatment wi the chromium salt solution before drying.

1; Examples V, VI, and VII of this specification are exemplary of the method of treating the delustered material after its formation. In the process it is preferable to use a water-soluble salt of chromium, but advantages of the invention may be obtained by treating the delustered material with a suspension of an insoluble chromium compound. The treatment with a water-soluble or with a water-insoluble compound is preferably given before dyeing, but advantages of the invention may be secured by treatment after dyeing.

Example V Artificial silk, delustered by the incorporation of titanium dioxide in the mass, is treated for half an hour at 85 C. in an 0.3% aqueous sodium bichromate solution, to which there may be added, if desired, 0.2% formic acid, and is dyed with Chlorazol Orange PO. Exposure to light before drying failed to produce determinable fading.

Example VI Artificial silk delustered by the incorporation of titanium dioxide in the mass was treated for half an hour at 85 C. in a 0.5% aqueous chromium chloride solution, and was dyed with Chlorazol Fast Black BK. No fading occurred on exposure to light either before or after drying.

Example VII Regenerated celulose artificial silk delustered by treatment with titanium dioxide and treated according to Examples V and VI is rinsed and dyed with 2% of the substantive dyestuff Chlorazol Fast Helio BK (C. I. No. 390) with the addition of 10% of Glaubers salt for three-quarters of an hour at 80 C. The dyeing thus obtained is of good fastness to light when in the wet condition whereas when not treated according to the present process the shade of the moist material is of poor fastness to light.

The processes of the invention are equally applicable to the manufacture of regenerated cellulose by any method and to the manufacture of esters and ethers of cellulose which have been delustered by incorporation into the spinning mass of titanium dioxide. The esters and ethers are not abnormally sensitive to light when wet, but there is a general decline in the fastness to light in dyeings on the dry fiber thus delustered.

:fiI By treating the titanium dioxide used for de ifstering purposes, either before or after incorporation in the spinning mass, and either before or after the formation of the end product with a soluble chromium compound such as chromium chloride, or chromium fluoride, or chromium trioxide, this increase in fugitiveness to light of dyeings on cellulose esters and ethers may be entirely prevented or appreciably diminished.

Titanium dioxide which has been incorporated with the fiber may be treated with chromium compounds either before or after dyeing, provided, however, that care is taken that any after-treatment does not undesirably affect the dyestufi on the fiber. Titanium dioxide which is to be treated prior to incorporation in a spinning mass, may also be treated with insoluble chromium compounds. For instance, titanium dioxide paste may be thoroughly mixed with freshly precipitatedchromium hydroxide, or chromium hydroxide may be precipitated in situ by stirring the titanium dioxide paste with a solution of a chromium sesquioxide salt in the presence of ammgr ia or an alkali carbonate.

IQ; Dyeings produced in the usual manner on acetate artificial silk delustered by titanium dioxide which has been treated with chromium are of improved fastness to light as compared with dyeings produced on similar material containing untreated delustrant.

{13; Examples VIII, IX, and X of this specification illustrate the applicability of the invention to dyeings on cellulose esters and ethers. Cellulose acetate was chosen in each instance because it is the most widely used of those compounds, but the processes are equally applicable Cellulose, acetate artificial silk delustered by incorporation of titanium dioxide in the mass bewellrinsed-anddyedin tom spinning, is treated, before dyeing, in a liquor containing 3 parts sodium bichromate-and 1 part formic acid (80%) for 1000parts water for one-halt hour at 85 C. The material is then the usual way.

- In place of sodium bichromate as abovethere maybe employed5 parts of chromium chloride or iiuoiride. Example IX Acetate-artificial silk is delustered by incorporating in the massbefore spinning titanium dioxide which has been treated in a liquor containing 10 parts sodiumcbichrornate for 1000 parts water for one-halt hour at 85 C. followed by' thorough rinsing, filtration and drying namely tungsten, molybdenum. and

In place 'of sodium bichromate in the above example there may be used parts of chromium chloride or fluoride and a similar eil'ect obtained.

Ezamplex Acetate artificial silk is delustered by incorporating in the mass oxide which has been mixed with sodi1un bi-' chromate in the proportion of 99 parts of the former and 1 part of the latter.

Q. The advantages of the .invention accrue not only to the water-soluble or water-insoluble compounds of chromium but can be obtained by the use of water-soluble cr water-insoluble metals in the. same periodic group as chromium, uranium. Artificial silk from regenerated cellulose or from incorporated in any of the above described methhas not been thus treated.

, delustrant is treated for ods with a water-soluble or water-insoluble salt of any of these elements. Such artificial silk in the wet or moist condition R. Examples in, m, xm, xw. xv, xvi,

1 and XVII illustrate the applicability of these compounds to the process.

7 Example Xi V Artificial silk containing titanium dioxide as which it is dium molybdate and 1 partformic acid per 1000' partswater. after which it is rinsed and dyed.

Example XIII which it is and dyed. reampi xiv Titanium dioxide intendedfor use as deluatrant is treated for one-half hour at 85 C. in a liquor before spinnin titanium di-' Titanium dioxideis treated with sodium molybdate the conditions described in Example XIV. Y

a v Example xvi Titanium dioxide is treated for one-half hour at 85 "nitrate per 1000 parts water after which it is weli-washul with water, filtered and dried.

I g i Example XVIL: v Titanium dioxide ..parts) is mixed with'sodium teor sodium molybdate (1 part) and the-whole employed as t. sample xvm 100 parts or titanium dioxide are treatedwith a solution 0151M perm chromium chloride at 85 C. and suineient dilute caustic soda solution (say 5%) gradually added under agitation to pre cipitate the chromium as chromium hydroxide.

C.inaliquorcontaining5partsuranium The resulting product is collected washed, dried and groimd.

Example XIX Y 99 parts of finely divided titanium dioxide are ground with 1 part of finely divided chromium sesquioxide until a homogeneous mixture. is ob- Example XX Artificial silk delustred by means of titanium dioxide is treated for half an hour at- 70 C. with an 0.2% aqueous solution of chromium trioxide.

" 8. Examples of direct colors have hereinabove T. 'Iheproceas of treatment which hashere-- inbefore been described prevents the rapid wetiading which has heretofore been a feature of deluster'ed rayon when dyed with direct cotton colors. The process permits dyeing with the dyestufis and processes commercially employed for dyeing rayon with direct cotton colors and makes the dyeing oi rayon a perfectly straightforward matter, which has not heretofore been the case. My delusfered rayon, when dyed with a' .diiectdyaisequalin ht iastness to similar undelustered material.

U. Great modifications and variations may be manyofitsphasesasisconsistentwiththespace which may be allotted to the disclosure of an in- "vention in a patent application. Obviously where can .be illustrated so many variables enter not all by a specific example. r

V. 'llhis application isa continuation-in-part 'of my priorapplication Serial No. 758,684, nowabandoned, filed December 21, 19

W. As many apparently widely diflerent defined in the ;I claim:

cellulose nbeited with a titanium oxide 7 t'o the specific embodiments thereof except as cellulose fiber delustrant, and sodium bichromate, and dyed with a direct cotton dye.

2. The material which cellulose fiber impregnated with delustrant, and a chromium compound, with a direct cotton dye.

3. The material which comprises a regenerated cellulose fiber impregnated with a titanium delustrant, and a. water-soluble chromium compound, and dyed with a direct cotton dye.

4. The material which comprises a regenerated cellulose fiber impregnated with a titanium oxide delustrant, and a water-insoluble chromium compound, and dyed with a direct cotton dye.

5. The material which comprises a regenerated cellulose fiber impregnated with a titanium oxide delustrant, and a compound of one of the metals of .the chromium group, and dyed with a direct cotton dye. I

. 6-. The material which comprises a regenerated cellulose fiber impregnated with a titanium oxide delustrant, and a water-soluble compound of one of the metals of the chromium group, and dyed with a direct cotton dye.

7. The material which comprises a regenerated impregnated with a titanium oxide delustrant, and a water-insoluble compound of one of the metals of the chromium group. 8. The material which comprises anv artificial cellulosic body impregnated with a titanium delustrant, and a compoundcf one of the metals of the chromium group.

9. The materiabwhich comprises an artificial cellulosic fiber impregnated with a titanium oxide delustrant,. and sodium bichromate.

10. The material which comprises an artificial cellulosic fiber impregnated with a titanium delustrant, and a chromium compound.

11. In the process of manufacturing a cellulosic body from a material of the comprises a regenerated a titanirm and dyed class consistingof cellulose esters, cellulose ethers, and regenerated cellulose, delustered with a titanium 'delustrant, the steps which involve treating the titanium delustrant with one of a group of materials. consisting of the compounds of the metals of the chromium group.

and dyed with a direct I prises treating the d'elustrant with a dyefixative 12. In the process of manufacturing a cellulosic body from a material of the class consisting oi cellulose esters, cellulose ethers, and regenerated cellulose, delustered with a tita um delustrant, the steps which involve treating the titanium delustrant with one of roup of materials consisting of the compounds of the metals of the chromium group before mixing it with the other ingredients.

13. In the process of manufacturing a "cellulosic body from a material of the class consisting of cellulose esters, cellulose ethers, and regenerated cellulose, delustered with a titanium the steps which involve treating the titanium delustrant with one of a. group of materials consisting of the compounds of the metals of the chromium group before the formation of the cellulosic body.

14. In the process of manufacturing a. cellulosic body from a material of the class consisting of' cellulose esters, cellulose ethers, and regenerated cellulose, delustered with a titanium delustrant, the steps which involve treating the titanium delustrant with one of a group of materials consisting of the compounds of the metals of the chromium group after the formation of the cellulosic body.

15. A composition of matter comprising an 7 aqueous caustic alkali solution of an alkali metal salt of cellulose xanthic acid, a titanium delustrant, and a chromium compound.

16. A composition of matter comprising an aqueous caustic alkali solution of an alkali metal salt of cellulose xanthic acid, a trant, and sodium bichromate.

1'7. A composition of matter comprising a cellulosic solution, a titanium delustrant, and a compound of a metal of the chromium group.

18. In the manufacture of delustred artificial cellulosic bodies containing a titanium d'elustrant dye,

titanium deluscomprising a metal of the chrocompound of a mium group.

HARRY DONALD MUDFORD.

the step which com- 7 

